Have lump under breast. Going to have ultrasound. No other symptoms. Lymphoma?

I have a lump under my breast on top of my rib. I have had it for years. It may have grown slightly. It is about 4 inches long and an inch wide and squishy. It is not painful except sometimes at nite after my bra has "dug" into it. The nurse called it a lymphoma. I am now booked for an ultrasound. When I looked up lymphoma it indicates cancer. Can this be a fat deposit and not cancer. I don't think I have any of the symptoms (fever, night sweats, itchiness) that go with lymphoma except night sweats but I am post menopausal so think it goes with that, and they are not too serious. I am just trying to consider this may not be a serious matter and could be something else. I didn't think to ask the doc if it was something else as I was having a general physical and there were lots of questions. I thought lymphoma was the general name for a "growth" not necessarily, cancer, until I looked it up on the internet. Thanks.

Based on the description of the lump, the rate of growth, associated symptoms and the site of involvement, I do not consider it to be lymphoma. Lymphoma lump does not remain unchanged for years or present slow growth.

I suspect the lesion to be a Lipoma (fat tumor) which is not cancerous. Do get the Ultrasound scan done, the scan may provide some insights into identify the diagnosis.

If the scan fails to give convincing results, do get a test called FNAC (Fine needle aspiration cytology). In this test, a small amount of material from the lump is taken using a needle and subjected under microscope to find out the exact diagnosis.